Showing papers on "Downstream processing published in 1989"

Frontiers in bioprocessing

Abstract: Problems and Challenges in the Production and Processing of Biologically Active Materials. PROCESS INTEGRATION. Development of a Reverse-Phase HPLC Process Step for Recombinant b-Interferon. Sensitivity Analysis of an Integrated Process of Lignocellulose Conversion to Ethanol. The Story of Biosynthetic Human Insulin. Purification and Sequencing of Interferons and Other Biologically Active Proteins and Polypeptides. ADVANCES IN FERMENTATION. Kinetics of Immobilized Cells: A Structured Model. Bioreactors and Models for Genetically Modified Organisms. Mammalian Cell Culture: An Overview of the Problems and Various Approaches for the Development of Large-Scale Systems. Use of Fungal Elicitors to Increase the Yield of Secondary Products in Plant Cell Cultures. Using a Structured Kinetic Model for Analyzing Instability in Recombinant Bacterial Cultures. Preliminary Analysis of a Hollow Fiber Extractive Fermentor for the Production of Ethanol. Simulation Results of Applying a Robust Multivariable Control Design Methodology to a Generalized Bacterial Growth System. RepA mRNA, a Potential Rate-Limiting Factor in Replication of R1 Plasmids. Bacillus subtilis as a Host of Recombinant Vectors: The Protease Problem. BIOSENSORS. Integrated Biosensors. Sensing Techniques for Bioprocess Monitoring and Control. Mass Fabricated Ion, Gas, and Enzyme Multispecies Sensors Using Integrated Circuit Technology. Flux Determination in Cellular Bioreaction Networks: Applications to Lysine Fermentations. BIOSEPARATIONS I: FREE FLUID METHODS. Analytical Cell Electrophoresis as a Tool in Preparative Cell Electrophoresis. Effective Principles for Scaleup of Electrophoresis. Electrophoresis Experiments in Space. Cell Partitioning in Two-Polymer-Phase Systems: Towards Higher Resolution Separations. Large-Scale Affinity Partitioning of Enzymes in Aqueous Two-Phase Systems. Computerized Strategy for Estimation of Protein Purity. BIOSEPARATIONS II: CHROMATOGRAPHIC METHODS. Purification of Proteins of Low Value in High Volume. High Performance Adsorption Separations. Preparative-Scale Chromatographic Processes: Ion-Exchange and Affinity Chromatographic Separations. Adsorption Chromatography: Approaches to Computer-Based Optimization and Modeling of Column Processes. Immobilized Metal Ion Affinity Chromatography of Transferrins. HPLC Scale Up for Uracil-DNA Glycosylase Purification. BIOSEP: A Novel Approach to Precompetitive Research in Downstream Processing. EMERGING TECHNOLOGIES IN BIOPROCESSING. Large-Scale Fluidized-Bed Bioreactor Systems. Multiphase Membrane Reactors for Enzymatic Resolution: Diffusional Effects on Stereoselectivity. Protein Engineering for the Development of Novel Affinity Separations. Microbial Metal Leaching and Resource Recovery Processes. Coal Biosolubilization.

Integration of bioconversion and downstream processing: starch hydrolysis in an aqueous two-phase system.

Abstract: Starch hydrolysis is one of the major processes catalysed by enzymes in industrial operation today. Since it deals with the enzymatic degradation of a macromolecular or even particulate substrate, the use of soluble enzymes has been preferred. Since the enzymes used are rather cheap, it has been possible to operate the process under economically acceptable conditions, in spite of the consumption of enzymes. However, the reaction time is long because the biocatalytic density is kept rather low, since the soluble enzymes are not reused.

The role of adsorption isotherms in the design of chromatographic separations for downstream processing

Abstract: Separation by some form of selective adsorption such as chromatography is an established method in the downstream processing of biological products. The aim of this work was to provide quantitative data which could be used in the construction, testing and verification of process models suitable for scale-up and optimisation. The use of ion exchange chromatography in the processing of amino acids was chosen as a model system

Large Scale Protein Recovery using Aqueous Phase Systems

Abstract: Aqueous phase systems provide not only a gentle environment for biologically active proteins [1,2] but offer unique possibilities for application in downstream processing, especially in large scale. Most important, a very difficult mechanical separation step can be replaced by an extraction process, which is thermodynamically controlled and allows the separation of cells or cell debris from a soluble protein by partition into opposite phases under suitable conditions [3–6]. Poly(ethylene glycol) (PEG)-salt systems, as well as two-polymer systems, may be employed for this purpose, the former appears to give a higher selectivity in protein partition and leads to an enriched product in the first extraction step in high yield [3-5]. PEG is commercially available as a bulk product with several molecular weight fractions in the interesting range 600-8000 dalton. PEG is usually chosen also as one of the polymers if a two-polymer system is investigated. The second component may be either purified dextran fractions (1,2), crude dextran (7), starch derivatives (8), or other polymers like polyvinylalcohol (9). The selection of the basic phase system depends on the partition coefficient of the product of interest and on economic factors, which are closely linked to the concentration required for phase formation. Single step yields and simultaneous purification of product have to be considered also in the design of the primary extraction step. The necessary separation of the two immiscible liquid phases can be carried out by conventional equipment at unit gravity or accelerated by centrifugal forces without major problems [3,7,10–12].

Downstream Processing — Solvent Extraction and Liquid Membrane Permeation

Abstract: Unit operations with intrinsic chemical reactions, like solvent extraction (SX) and liquid membrane permeation (LMP), offer the possibility to design selective separation processes Ion exchanger types used for downstream processing are discussed The influence of chemical parameters on the separation of an amino acid (1-phenylanaline) is shown as an example A comparison of LMP and SX technique is given with emphasis on the difference of mass transfer mechanism and devices needed

Biomimetic Dyes in Biotechnology

Abstract: Downstream processing refers to all the technologies that are responsible for the production of pure products after fermentation. Therefore, if one were to produce, for example, a protein, one would start with an appropriate bio-reactor containing native or engineered cells. The first step would be to separate the cells from the broth; if the product is an intra-cellular one, one would subsequently disrupt the cells to release the intra-cellular products and then embark on a clarification process to obtain a clear extract containing the protein of interest. The next step is to apply a whole series of high resolution purification techniques, particularly chromatographic steps, prior to subsequently ending up with pure protein. Therefore, downstream processing entails the execution of primary recovery stages followed by a series of high-resolution steps where we add value to the final product and then hopefully end up with pure homogeneous protein. Special interest is focused in this report on the high resolution stages of the process leading to pure product and particularly those steps involving the most refined version of chromatography, affinity chromatography (1). The technique of affinity chromatography exploits small ligands which bind specifically and reversibly to the protein of interest. The appropriate small ligand is covalently attached to a suitable solid support matrix in such a way that we can establish that as a column.

Continuous Crosscurrent Extraction of Proteins in Process Scale

Abstract: Automated continuous cross-current extraction of intracellular microbial enzymes from disrupted cells has been studied using a two-stage plant capable of processing 20–30 kg biomass per hour. The results reveal the feasibility of this advanced method of downstream processing by aqueous two-phase extraction.

Fast downstream processing of proteins by flocculation and liquid extraction

Abstract: The initial downstream processing of intracellular microbial enzymes is usually conducted in the sequence: cell harvesting→cell disruption→ clarification→ initial enrichment. The efficiency of the conventional recovery route — most importantly the space-time yield, but also the activity yield — can often be increased considerably by using flocculation, mechanical cell disruption and liquid extraction. A further enhancement of the space-time yield or reduction in process time, respectively, may be obtained by the integration of single steps to semi or fully continuous processes. These topics are discussed in this paper using the downstream processing of fumarase from Brevibacterium ammoniagenes as a case example based on experiments conducted in pilot/commercial scale.

Downstream Processing of Potato Proteins

Abstract: Plant proteins are used widely in the food industry, either for processing, conditioning or supplementing human and animal dietary materials. Many plants have considerable potential as sources of enzymes and other proteins for use in medicine or the production of fine chemicals and pharmaceuticals. A number of plants are suitable as host organisms for the production of recombinant healthcare proteins. Unlike plant proteins used in the food industry, the new range of enzymes and proteins will require considerable purification before use. Aspects of the problems of downstream processing of plant proteins are discussed, using potato tuber-specific proteins as examples.

Applications of Chromatography in Downstream Processing

Abstract: The eukaryotic cells have the natural property of synthetizing or secreting proteins into the medium and by that way, they represent an excellent tool for producing biomolecules. This principle is being widely applied in the preparation of proteins of therapeutic or diagnostic interest (lymphokines, interferons, tissue plasminogen activator, monoclonal antibodies, …).